mod_perl is one of the most
veteran and successful Apache projects. It embeds a Perl interpreter
in Apache and allows access to the web server internals from
Perl. This allows for entire modules to be written in Perl or a
mixture of Perl and C code. In the 1.3 Apache versions, one
interpreter has to be embedded in each child, since the server is
multiprocess based. In heavy traffic dynamic sites, the increased
size could make a difference. Apache 2.0 is multithreaded, as recent
versions of Perl are. The next generation of mod_perl takes advantage
of this and allows for sharing of code, data and session state among
interpreters. This results in a faster, leaner solution.